Integrated Photogrammetric Data Analysis and Discrete Fracture Network Modeling to Determine Rock Structure Around Excavation at El Teniente Mine

摘要

In underground mining, the excavations instability problems depend essentially on the stresses and rock mass characteristics. The stresses are associated with in situ conditions (depth, tectonism or others) and with induced conditions by excavations (size and shape). It has been observed that in most of geotechnical instabilities at El Teniente mine (rock bursting and wedges) that always rock damage is structural controlled, and then it seems to be a relevant task during mining operations to get the best knowledge and description of the rock structure surrounding excavations.Discrete Fracture Network (DFN) modelling has been introduced in the mining industry as a way to obtain a better statistical representation of a fractured or structural controlled rock mass such as El Teniente primary ore. Because the parameters needed to build a DFN (orientation, size and intensity) are far more specific, the final result will be step forward in comparison with the use of traditional classification system.Recently technological innovation for tunnel geological mapping introduced at El Teniente mine such as the 3D digital photogrammetric allow to perform a detailed description of the rock fabric (rock structure) of the rock mass. A single photogrammetric file or image, named as Digital Terrain Models (DTM), represents between 3 and 4 meters of a tunnel development, and then more than 200 of geological strictures can be described in term of their basic parameters (dipdir, observed trace length and location in mine coordinate system).Through a detailed data collection of more than 70 DTMs from different mine sectors (Esmeralda and Reno), a methodology to build a DFN for each single tunnel advance is described in this work. Following the simulated sampling technique to obtain the discontinuity size and intensity considering different truncation bias a DFN that honor the observed structural data was reached. Main results indicate that vein intensity known as P32 m2/m3 (fractured area/volume) surrounding excavation within Cmet rock mass vary from 2 to 7 m2/m3 considering a sampling cut off by 0.5 meters.